I use this on my 4 stroke MX bike where the pipe passed under the shock. This reduces heating of the shock caused by the hot exhaust. I use two layers and secure it with safety wire. You can tell the difference by touch with and without.
it will help a little with the overall heat reductions but a heat sheild is always a good thing to have to prevent burning your leg... one thing to remember with useing heat rap is it keeps the heat in so that means higher exhaust tempature.